Head phone



Jan. 9, 1940.- w, H HUT 2,186,072

HEAD PHONE Original Filed June 22, 1936 Patented Jan. 9, 1940 UNITEsrres PATENT OFFICE.

HEAD PHONE Walter H. Huth, Chicago, 111., assignor to Aurex Corporation,Chicago, 111., a corporation of Illinois 5 Claims.

This invention relates to so-oalled head phones for telephone apparatus,and more especially those that have an ear-piece for eachear.

This application is a division of co-pending 5 application Serial No.86,504, filed June 22, 1936, now Patent No. 2,107,416, issued Feb. 8,1936.

Generally stated, the object of my invention is to provide an improvedconstruction and arrangement whereby one ear-piece of a double headphone has a variable resistance, whereby to balance the efiect in bothears, for a person whose hearing is not the same in both ears, incombination with volume control.

It is also an object to provide certain details and features ofconstruction and combinations tending to increase the general efficiencyand desirability of an apparatus of this particular character. v

To the foregoing and other useful ends, the invention consists inmatters hereinafter set forth and claimed and shown in the accompanyingdrawing, in which Fig. 1 is a perspective of a head phone embodying theprinciples of the invention.

- Fig. 2 is a side elevation of one of the earpieces, on a larger scale,partly in vertical section.

Fig. 3 is a front elevation of the ear-piece shown in Fig. 2, on asmaller scale, with a cover plate shown removed.

Fig. 4 is an enlarged detail section on line 44 in Fig. 3.

Fig. 5 is a diagram of the circuits of the head phone and the power lineconnection.

Fig. 6 is a front elevation of the plug of said connection.

As thus illustrated, the invention comprises an ear-piece l of thedouble head phone, provided with a variable resistance in the form oftwo par- 40 allel strips 2, of suitable resistance material, connectedin shunt in. the circuit of this earpiece, so that this resistance is inshunt of the active element of the ear-piece, together with a metalslide-piece 3 engaging both strips of resistance, the slide-piece havinga handle 3 extending through the slot 5 in the casing t for enclosingthis variable resistance. By moving the handle l along the slot 5, theresistance will be Varied, and in this way the ear-piece I can beregulated to increase or decrease the strength of the action therein, inorder to balance the sound in both ears, for a person whose hearing isnot the same in both ears. In this way, and with the variable resistanceI in the connection plug 8, each person can regulate the head phone inaccordance with the hearing, and in a manner to balance the volumeefiect in both ears. It will be understood that the plug 8 is at the endof "the cord 9 leading from the head phone, and that I, the resistance 1is in shuntof the resistance 2 and 2 and is in bridge of the main linell] of .the apparatus. The movable contact I i, as shown, is in serieswith the resistance 2 of the head phone. Thus the resistance 1, or anyportion thereof, can

be included in series with the head phone. 10

Obviously, the variable resistance 1 will operate as a volume control,so that the volume can be regulated or controlled without disturb ingthe balance obtained, as between the two ear-pieces, by the adjustmentof the variable resistance on the ear-piece I, for when the balance isobtained, it then does not need to be disturbed in order to vary orcontrol the volume.

Thus, with people whose hearing is not the same in both ears, thevariable resistance 2 can be used to regulate the relative effect in thetwo ear-pieces shown in Fig. 1 of the drawing, to insure in efiect tothe user or listener practically the same volume effect in both ears, asby careful adjustment of said resistance the telephonic message willsound substantially as loud in one car as in the other. Thereafter,without disturbing said adjustment, the variable resistance 1 and I Ican be employed to regulate the volume effect in both ears, inasmuch asthe resistance 1, although bridged on the main circuit In and. normallyin shunt of the double head phone, is adapted by movement of the contactII to be included entirely or in part in series with the head phones. Asshown in Fig. 5 of the drawing, 5 only a relatively small portion of theresistance 1 is in series with the headphone, but by swinging thiselement H to the left, it is obvious that a greater portion can be thusincluded in series with the receiving instrument, so that after bal- 40ancing the effect in the two cars, so to speak, the volume control canthen be regulated without disturbing the said balance.

As is well known, and as indicated in Fig. 2, the casing of an ordinaryear-piece of a double head phone of this kind is commonly made of rubberor vulcanite or other insulating material. As indicated in Fig. 2, thetwo flat resistance strips 2 are preferably secured to a base strip ofinsulation, shown in section in Fig. 2, and the unitary flat structurethus formed is then fastened fiatwise upon the outside of the outer wallof the casing of the ear-piece, in any suitable or desired manner. Thenthe cover 6, with the handle 4 of the slide 3 protruding through theslot 5, is then fastened in place to the said casing, by the screwsshown at top and bottom in Fig. 2 of the drawing, so that the slot 5will be vertical, thereby making it easy to adjust the shunt resistancethus formed by straight up and down sliding movement for the desiredpurpose. Thus the invention can be applied to any ear-piece of thiskind, as an attachment for the outside thereof, instead of having to bebuilt into the earpiece when the latter is originally constructed. Thetwo wires of the cord connection 9 extend under the cover 6, asindicated in Fig. 1 of the drawing, and lead to the two large screwsshown in Fig. 4 of the drawing, which screws have metal portions thatextend toward each other and engage the flat strips 2 in the mannerclearly shown in Figs. 3 and 4 of the drawing. Thus the cover 6 can beeasily removed to repair the adjustable shunt resistance thus provided,if necessary or desirable.

What I claim as my invention is:

1. The combination of a double ear-piece head phone, with each ear-piececonnected in the same circuit, so that they simultaneously receive themessage, and adjustable shunt resistance means disposed fiatwise on theoutside of the outer wall of the casing of one ear-piece, havingstraight sliding movement to vary the resistance of the shunt, afiectingthe active element thereof, in series with the active element of theother earpiece, thereby to balance the volume efiect in both ears.

2. A structure as specified in claim 1, and a separate volume control incircuit with both earpieces.

3. A structure as specified in claim 1, and a separate volume control incircuit with both earpieces, with a portion thereof always in shunt ofeach ear-piece, this separate control being incorporated in a switchplug at the end of a flexible cord leading to said phone.

4. A structure as specified in claim 1, comprising a second volumecontrol in shunt of said adjustable shunt resistance and in shunt of theactive element of each ear-piece.

5. A structure as specified in claim 1, comprising a casing coveringsaid shunt resistance, fastened to the outer side of the ear-piece, witha vertical slot in said casing, and a contact member slidable in saidslot and engaging the shunt resistance, the latter comprising parallelfiat'strips insulated from each other and included in series in theshunt circuit.

WALTER H. HUTI-I.

